Scripted by Trier and his usual collaborator Eskil Vogt, Thelma catches up with the shy student, when she has just left her religious small town family to study at the university in Oslo. Shortly after semester start she experiences a violent, unexpected seizure at the library, and soon after, she finds herself intensely drawn towards Anja, a beautiful student who reciprocates her powerful attraction.

Thelma becomes increasingly overwhelmed by her intense feelings for Anja, which she doesn’t dare acknowledge, even to herself, while at the same time experiencing more extreme seizures. As it becomes clear that they are a symptom of inexplicable, often dangerous, supernatural abilities, Thelma is confronted with tragic secrets of her past, and the terrifying implications of her powers.